Arrangement for amplifying high-frequency currents



April 28, 1925. v 1,535,182

- w. SCHAFFER ARRANGEMENT FOR AMPLIFYING HIGH FREQUENCY CURRENTS Filed Aug. 18, 1922 2 ShGDS-ShGei l Fwy e fi'mvewtoz I WALTER SCHAFFER Alarm u ARRANGEMENT FOR AMPLIFYING HIGH FREQUENCY CURRENTS Filed Aug. 18, 1922 2 wimgz Sheets-She e't 2 Swwamtoz WALTER SCHAFFER @331 his flbtomwlgg/jy Patented 325%,

IWALTEE BERLIN, GERMANY, ASSIGNOJF.

DRAHTLOSE TELEGMl-PHIE M. B. H. HALLESCHES, 0F BERLIN, GE'RILEANY, A UUFM ZPORATTON' OFGEREHAIT'TZ'.

ARRANGEMENT F0155 AMPLIFYING HIGH-FREQUENQY CURREfilTS.

v .Fin licatina filed August 18, 1222. Sriatlt'o. 582,809.

To all whom it may concern Be it known that If, WALTER SCHAFFER, a citizen of the Republic of Germany and a resident of Berlin, Germany, have invented certain new and useful improvements in Arrangements for Amplifying High-Fre-' quency Currents, of which the following is a specification, accompanied by drawings.

As is well known, thenumber of stages through which a high frequency current may be amplified is limited by the fact that, due to internal back coupling, the amplifying arrangement energizes itself. The invention relates to an arrangementwhich ob-' In accordance with the invention the ar-.

rangement is so provided that at each frequcncy'transformation a new amplification is obtained.

In the drawingin which like reference numerals designate like parts in the various views;

Fig. 1 is a diagrammatic representation of an auxiliary circuit arrangement which may be employed for frequency transformation in the practice of the invention;

Fig. 2 is a diagrammatic representation of a modified circuit arrangement adapted for use for the same purpose as the arrangement shown in Fig. 1; and

Fig. 3- is a diagrammatic representation of a circuit arrangement embodying the invention and including the auxiliary circuit arrangements shown in Figs. 1 and 2.

Auxiliary means of widely varying char- "acter may be employed for the purpose of frequency transformation. In order, however, to obtain at this frequency transformation also an amplification, it is preferable to use in the high frequency amplification intermediate elements such as the circuit arrangements shown in Figs. 1 and 2 of the drawings. The circuitnrrangement shown in Fig. 1 comprises a direct current source 1 for a generator tube 2 which is coupled with the oscillating circuit 3. The oscillating circuit 3 may be tuned to any desired frequency. The cathode side of the current supply circuit of the generator tube 2 comprises a three element tube 1 the grid of which is bridged by a resistance or grid leak 5 for the purpose of the grid discharge. The purpose of the battery 6 is to supply such a negative auxiliary potential to the grid that the generator tube 2 produces 0scillations only when the tube 4 is controlled by the energy existing at points Send 9. This energy may be obtained from a transformer 7 which constitutes the end of a suitably increased high frequency amplifiro eusatascnarr cation. The energy is received in the tuned circuit 10 and is rectified by means of any suitable rectifying circuit 11. The direct current potential difierences between points 8 and 9 are always in proportion with the energy existing in transformer 7. This direct current potential difference controls the cathode tube 2 and thereby also controls the oscillations produced in circuit 3 by said tube. At the same time, due to the generative action of tube 2, these oscillations in circuit 3 have a larger amplitude. By means of a transformer 12 these oscillations are transmitted from oscillating cir cuit ,3 into a further high frequency amplifier set. I

The clrcuit arrangement shown in Fig. 2

operates in a manner similar to the arrangement shown. in Fig. 1 but differs from the arrangement shown inFig. 1, in that the control of the oscillations in the circuit 3 is not effected by means of a tube 4 but by directly actuating the grid of the generator tube 2. For this purpose the grid coil 13 is inductively connected with the circuit 3 and is connected with the cathode through the condenser 14. The purpose of the auxiliary battery is the same as was the case in Fig. 1; namely, in the absence of oscillations in transformer 7, the battery causes the generator tube 2 not to produce oscillations. As in the arrangement shown in Fig. 1, the resistance 5 serves as a grid leak to preventthe grid potential from becoming excessive.

A complete high frequency circuit arranged in accordance with the present invention is shown in Fig. 3. The receiving antenna l5 is associated with the first-high frequency amplifier 17 of a set composed of a suitable number of individual amplifiers,- the amplifiers of each set being limited to a number such as will obviate self-energization of the amplifier due to -internal backcoupling. It; hasi-been found that three I amplifiers of the usual construction is as large a number as' can be used without injurlous back-coupling, and, accordingly, the

" amplifiers 17 are shown in Fig. '3 of the drawings as three in number. The energy thus amplified is transmitted to a frequency converter 18 such as the one shown in Fig. 1. The energy that is simultaneously transformed and amplified is transmitted through transformed energy is taken 0 verted frequency at 12 and transmitted to an additional amplifier set 21 from which .a transformer to aset of amplifiers'lf), also of suitable number, and is taken off at 7 by a frequency converter 20 such as the one shown in Fig. 2. The am lified and at a conit may again-be taken off at 21'. This circuit arrangement may be re eated as often as desired vuntil in the end t e total amplification produces the required loudness. Obviously, the above described arrangement may be applied also to low frequency ampli-' fication ecause the frequency converters may without difliculty be operated for low frequency. I In view of the fact that in the frequency between thedifie'rent amplifying stages.

Having'de'scribed my invention what I claim is 1. An arrangement for amplifying ,alternating currents comprising alternate ampli fiers and frequency transformers, each of said transformers comprising a vacuum tube having a grld, a receiving circuit connected to the grid and a rectifier in the receiving circuit connected directly with the gridfor causing direct current-potential in proportion to the received energy to be impressed on the grid and for preventing any back I effect of the transformer on the preceding said transformers having individual amplification and comprising avacuum tube generator havinga grid, a receiving circuit connected to the grid, and-rectifiers in the receiving circuit for causing directcurrent potential in proportion to the received energy to .be impressed on the grid and for preventing any back effect of the transformer on the preceding amplifiers. "I

3. An arrangement for amplifying alternating currents comprising a source of energy, means for amplifying the received energy through a suitable number of stages, an oscillation generator, a receiving circuit for controllingthe oscillations in the generator, sai receiving circuit being arranged to receive the amplified energy from the amplifyingmeans, a rectifier in the receivmg circuit for preventing the occurrence of anyback effect between the oscillation generator and the amplifying means, and means for further am hfying the energy of the oscillating circuit of the oscillation genera tor through a suitable number of stages.

4. An arrangement for amplifying alternating current, comprising a source of current, a first amplifying means for amplifying said current, a, second'amplifymg means, and a frequency transformer between said first and second means, .saidfrequency transformer having associated therewith a double rectifier arranged so as to prevent back-coupling between said first and secondmeans.

WALTER SCHAFFER. 

